Combined plural carrier electrostatic printing and display system



W W? WTSWW" U KR 3 1 5 0 LMUQJQ ELK :LMLHMMM Mm M1 @111 COMBINED PLURAL CARRIER ELECTROSTATIC PRINTING a AND DISPLAY SYSTEM J a 1 Filed Jan. 13, 1960 l I m INVENTOR.

GEWGE w. BA/N ATTORNEY United States Patent 3,148,600 COMBINED PLURAL CARRIER ELECTRCSTATIC PRINTING AND DISPLAY SYSTEM George W. Bain, Fort Wayne, Ind, assignor to international Telephone and Telegraph Corporation, Nutley,

N.J., a corporation of Maryland Filed Jan. 13, 1960, Ser. No. 2,274 8 Claims. (Cl. 95-]..7)

This invention relates to an electrostatic printing display system, and particularly to an electrostatic printing display system to provide multicolor displays.

When a large amount of information is to be displayed in a minimum time, the direct printed large area electrostatic method has proven very useful. This method is simple compared to other systems in that the electrostatic printer is capable of accepting input information from computers or other sources and directly printing the information in the desired size in a display area.

In the present specification the term printing and related terms as used in relation to electrostatic printing are to be understood as involving no mechanical pressure whatsoever in effecting the printed image, but relate instead merely to the deposition of some type of ink on a suitable medium to form an image not necessarily of any permanence. Further, it is to be understood that the term image as herein employed is used to include letters, figures, words, characters, pictures, and all other representations which may be printed on the aforesaid suitable medium.

Electrostatic printing as known in the prior art usually employs a movable, insulated, opaque belt which is electrostatically charged in given image patterns as the belt passes a multiple element printing head. After being electrostatically charged the belt is passed in close proximity to a source of powdered insulating material (termed ink) of a distinct color, usually black. The ink is attracted by the electrostatic charge pattern and adheres to the belt. The belt is then moved to a display position where the powder adhering to the charge pattern can be viewed in a manner similar to black printing on a light background. After the information is viewed, the belt is moved past electrostatic discharge heads which remove the insulating powder, which powder may be subsequentially recovered and reused.

In many cases it is desired to display information derived from a plurality of sources, or information having distinct parts, which information from the plurality of sources or from the distinct parts is related and is preferably viewed in a physical relationship to each other. Thus, for example, in displaying the positions of a number of aircraft in a given area, information as to altitude and velocity may also be Wished to be displayed adjacent the representations of the corresponding aircraft but in such a manner as not to confuse or clutter the display. Thus, it is seen that a technique for displaying composite printing is desirable, and particularly one in which the different components are distinct, such as by displaying different colors.

It is further desirable that the display of such printed information be of maximum brightness and clarity.

An object of the present invention is to provide an improved electrostatic printing display system, particularly one providing a composite display, especially a multicolor composite display.

A feature of the present invention is the provision of an electrostatic printing display system comprising a medium having an electrostatically printed surface, and means to display the printed surface of the medium, the display means including a source of polarized light illuminating the medium and an optical filter responsive to the light and orthogonally polarized relative thereto.

Another feature of the present invention is the provision of an electrostatic printing display system comprising a plurality of mediums having electrostatic printing on the surfaces thereof, means to combine the mediums to form a composite printed image, and means to display the composite printed image.

The above-mentioned and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawings, the single figure of which illustrates one embodiment of a display system following the principles of this invention.

Referring to the drawing, an electrostatic printing dis play system is shown comprising a medium 1 having printing thereon, means 2 to display the printed surface of the medium 1, the display means 2 including a source of polarized light 3 disposed on one side of the medium, source 3 including a light source 4 and a first light polarizing filter 5, and a second light polarizing filter 6 disposed on the other side of the medium, filter 6 being polarized orthogonally relative to filter 5, and means to remove the printing from medium 1 after display. Filters 5 and 6 may be composed of a light polarizing material sold under the Trademark Polaroid.

Medium 1 can consist of a single belt 1 of transparent dielectric material, such as a transparent dielectric ma terial sold under the trademark Mylar, suitable for electrostatic printing purposes; however, for composite dis play purposes medium 1 is composed of a plurality of such 1 1 1 1 concentrically positioned with respect to each other. During most of the operation of the present display system belts 1 1 1 1 are brought closely together to form a multilayer belt, and if need be, may be so held together by electrostatic attraction by charging the outer edges of the individual belts.

The printing on medium 1 is accomplished by printing means 9 in a manner to be now described. Medium 1 is movable and is advanced by a friction roller drive 8. At an appropriate point the belts are physically separated and each belt is passed in close relation to a separate one of a plurality of multiple element electrostatic printing heads 9 9 9 9 presently available in the prior art, which electrostatically charge given predetermined areas of each belt. Each belt is then advanced past a separate one of a plurality of sources of ink supply 10 10 10 10 which contain powdered insulating material (ink). The particles of the ink powder should be light reflective or light refractive for reasons to be later explained. The ink is attracted by and adheres to the charged areas of each belt. The ink contained in the separate ink supplies is differently colored. After the ink has been deposited, the belts are brought closely together to again form a multilayer belt. The printed areas of the separate belts are predetermined so that a composite multicolor image is formed by the multilayer belt with no overlapping of the separate printed areas. The multilayer belt is then advanced to display means 2.

Display means 2 includes a light source 4 and a light polarizing filter 5 which acts as a polarizer and provides a source 3 of polarized light on one side of medium 1. The polarized light from source 3 is transmitted through the multilayer belts of medium 1. The light will pass through the transparent dielectric material of the belts without being affected, but the light striking the printed portions of medium 1 will be depolarized due to the refiection or refraction caused by the ink particles. If reflecting ink particles are used the light will be depolarized as the light reflects from the surfaces of the particles, and if refracting particles are employed the light will be depolarized as the light propagates through the particles. The light which passes through medium 1 is passed through light polarizing filter 6 which acts as an analyzer and has a field of polarization orthogonal to that of filter 5. The polarized light which passes through the transparent dielectric material of medium 1 without being affected will thereby be inhibited by the polarization of the second filter. However, the portion of the polarized light source which was refracted or reflected by the particles of the ink forming the printed image will be depolarized and therefore be visible through filter 6, thereby providing a bright image display of the printed areas on a substantially black background.

After being displayed, means 1 is advanced to a means 7 to remove the ink. The composite belt is again separated and each one of the belts 1 1 1 1 is passed between discharging heads 11 11 11 11 which remove the electrostatic charge from the belts. The belts are wiped clean of the ink by wipers 12 12 12 12, and the ink is then collected in bins 13 13 13 l3 for later reuse. Belts 1 1 1 1 are then recombined into a composite belt and may be recycled for further printing and display operations. It is also possible to store medium 1 after the printing operation so that medium 1 may be held until desired and then brought forth quickly for display. Belt storage loops 14 and 15 are provided to accomplish this result.

It may be desired to retain the printed image in permanent form. In such event the powdered insulating ink material could be permanently afiixed to medium 1 by supplying a heat source to fuse the powder to medium 1 after printing, and ink removal means 7 would not be required. The sources of ink supply 10 10 10, may be arranged to provide any combinations of colors desired in the composite image, and one or more of the sources may be arranged with the same color ink to produce an image of a single color on one or more of the belts if such is desired.

The invention described hereinabove greatly increases the capabilities and usefulness of the electrostatic printing art. Information from several sources can now be recorded and be maintained distinctly identifiable by use of separate distinguishing colored ink. Also, image displays may now be color coded to convey additional information to the viewer. The display is also made relatively brighter and more distinct due to the fact that all background light is eliminated and only the inked portions of the display are seen by the viewer.

While I have described above the principles of my invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

I claim:

1. An electrostatic printing display system comprising a plurality of movable transparent dielectric printing mediums, a plurality of sources of ink in the form of a powdered dielectric material having predetermined light transmitting characteristics, a plurality of electrostatic printing means, each one of said printing means employed to transfer ink from a separate one of said ink sources to separate predetermined areas on the surface of a separate one of said printing mediums, said separate predetermined areas of each printing medium being different from the separate predetermined areas of each of said other printing mediums, means to combine said mediums in a superimposed relationship to form a composite printing, and means to display said composite printing of said combined mediums.

2. An electrostatic printing display system comprising a plurality of movable transparent dielectric printing mediums, a plurality of sources of ink in the form of a powdered dielectric material having predetermined light transmitting characteristics, the ink of each source being a separate color, a plurality of electrostatic printing means, each one of said printing means employed to transfer ink from a separate one of said ink sources to separate predetermined areas on a separate one of said printing mediums, said separate predetermined areas of each printing medium being different from the separate predetermined areas of each of said other printing mediums, means to combine said mediums in a superimposed relationship to form a composite multicolor printing, and means to display said composite multicolor printing.

3. An electrostatic printing display system comprising a plurality of movable transparent dielectric printing mediurns, a plurality of sources of ink, said ink including powdered dielectric material having a predetermined light transmission and light reflective characteristic, a plurality of electrostatic printing means, each one of said printing means employed to transfer ink from a separate one of said ink sources to separate predetermined areas on the surface of a separate one of said printing mediums, said separate predetermined areas of each printing medium being different from the separate predetermined areas of each of said other printing mediums, means to combine said mediums in a superimposed relationship to form a composite printing, a source of polarized light directed through said combined printing mediums such that said composite printing reflectively depolarizes said light, and an optical filter located opposite said combined mediums and responsive to said light, said filter being polarized orthogonally relative to said light to inhibit said polarized light and transmit said reflected depolarized light to provide a visual display of said composite printing.

4. An electrostatic printing display system comprising a plurality of movable transparent dielectric printing mediums, a plurality of sources of ink, said ink including powdered dielectric material having a predetermined light transmission and light refractive characteristic, a plurality of electrostatic printing means, each one of said printing means employed to transfer ink from a separate one of said ink sources to separate predetermined areas on the surface of a separate one of said printing mediums, said separate predetermined areas of each printing medium being different from the separate predetermined areas of each of said other printing mediums, means to combine said mediums in a superimposed relationship to form a composite printing, a source of polarized light directed through said combined printing mediums such that said composite printing refractively depolarizes said light, and an optical filter located opposite said combined mediums and responsive to said light, said filter being polarized orthogonally relative to said light to inhibit said polarized light and transmit said depolarized light to provide a visual display of said composite printing.

5. An electrostatic printing display system comprising a plurality of movable transparent dielectric printing mediums, means to electrostatically print a separate color on separate predetermined areas of the surface of each one of said mediums, said separate predetermined areas of each printing medium being different from the separate predetermined areas of each of said other printing mediums, means to combine said mediums in a superimposed relationship to form a composite multicolor printing, means to display said composite printing, said display means including a source of polarized light illuminating said printing mediums, and an optical filter responsive to said light and polarized orthogonally thereto to provide a visual display of said multicolor printing.

6. An electrostatic printing display system comprising a plurality of movable transparent dielectric printing mediums, a plurality of sources of ink in the form of powdered dielectric material having predetermined light transmitting characteristics, the ink of each source being a separate color, a plurality of electrostatic printing means, each one of said printing means employed to transfer ink from a separate one of said ink sources to separate predetermined areas on a separate one of said printing mediums, said separate predetermined areas of each printing medium being different from the separate predetermined areas of each of said other printing mediums, means to combine said mediums in a superimposed relationship to form a composite multicolor printing, a source of polarized light illuminating said printed mediums, and an optical filter responsive to said light and polarized orthogonally relative thereto to provide a visual display of said multicolor printing.

7. An electrostatic printing display device comprising a plurality of movable transparent dielectric printing mediums, a plurality of sources of ink, the ink of each source being a powdered dielectric material of a different color having a predetermined light transmission and light reflective characteristic, a plurality of electrostatic printing means, each of said printing means employed to transfer ink from a separate one of said ink sources to separate predetermined areas on the surface of a separate one of said printing mediums, said separate predetermined areas of each printing medium being different from the separate predetermined areas of each of said other printing mediums, means to superimpose said transparent mediums to form a composite multicolor printing, a source of polarized light directed through said combined printing mediums such that said composite printing refiectively depolarizes said light, and an optical filter located opposite said combined mediums and responsive to said light, said filter being polarized orthogonally relative to said light to inhibit said polarized light and transmit said reflected depolarized light to provide a visual display of said multicolor printing.

8. An electrostatic printing display device comprising a plurality of movable transparent dielectric printing mediums, a plurality of sources of ink, the ink of each source being a powdered dielectric material of a different color having a predetermined light transmission and light reflective characteristic, a plurality of electrostatic printing means, each of said printing means employed to transfer ink from a separate one of said ink sources to separate predetermined areas on the surface of a separate one of said printing mediums, said separate predetermined areas of each printing medium being difierent from the separate predetermined areas of each of said other printing mediums, means to combine said mediums in a superimposed relationship to form a composite multicolor printing, a source of polarized light directed through said combined printing mediums such that the refraction of said composite printing depolarizes said light, an optical filter lo cated opposite said combined mediums and responsive to said light, said filter being polarized orthogonally relative to said light to inhibit said polarized light and transmit said refracted depolarized light to provide a visual display of said multicolor printing, and means to remove said printing from each of said mediums after display.

References Cited in the file of this patent UNITED STATES PATENTS 1,169,098 Thornton Jan. 18, 1916 1,760,156 Mann May 27, 1930 2,123,743 Pratt July 12, 1938 2,143,214 Selenyi Jan. 10, 1939 2,167,518 Lins July 5, 1939 2,286,569 Pollack June 16, 1942 2,289,714 Land July 14, 1942 2,343,775 Land Mar. 7, 1944 2,393,969 Burchell et a1 Feb. 5, 1946 2,454,280 Hardesty Nov. 23, 1948 2,501,446 Justice Mar. 21, 1950 FOREIGN PATENTS 723,534 Great Britain Feb. 9, 1955 

1. AN ELECTROSTATIC PRINTING DISPLAY SYSTEM COMPRISING A PLURALITY OF MOVABLE TRANSPARENT DIELECTRIC PRINTING MEDIUMS, A PLURALITY OF SOURCES OF INK IN THE FORM OF A POWDERED DIELECTRIC MATERIAL HAVING PREDETERMINED LIGHT TRANSMITTING CHARACTERISTICS, A PLURALITY OF ELECTROSTATIC PRINTING MEANS, EACH ONE OF SAID PRINTING MEANS EMPLOYED TO TRANSFER INK FROM A SEPARATE ONE OF SAID INK SOURCES TO SEPARATE PREDETERMINED AREAS ON THE SURFACE OF A SEPARATE ONE OF SAID PRINTING MEDIUMS, SAID SEPARATE PREDETERMINED AREAS 